The invention relates generally to graphics processing and more particularly to a method and apparatus for graphics processing using parallel graphics processors.
Computers are used in many applications. As computing systems continue to evolve, the graphical display requirements of the computing systems become more demanding. This is especially true in applications where detailed three-dimensional graphical displays must be updated quickly. One example of such an application is a computer game where movement and modification of numerous images on the screen may place great demands on the processing power of the computing system.
In a typical video graphics processing system, a single graphics processor utilizes a frame buffer that stores color and Z information for each of the pixels that make up the display frame. The graphics processor renders images into the frame buffer, where the rendering may include comparing color and Z values of received or generated image data with that already stored in the frame buffer. Once rendering of the display image has completed in the frame buffer, the color data stored in the color portion of the frame buffer is read out and used to generate the display signal that is provided to the display. As the complexity of images increases and the processing operations corresponding to those images also increases, the processing requirements may exceed the processing limitations of such graphics processors.
One technique that can increase the graphics processing bandwidth in a system is to employ multiple processors to perform the graphics processing operations. Prior art systems that incorporated multiple processors to perform the graphics processing. for a single display have suffered from a number of drawbacks that reduce their efficiency of operation and cost effectiveness.
One such prior art system employed two processors where each processor has its own local memory for performing the graphics processing operations. Each graphics processor produced a display stream based on the portion of the display frame that it was responsible for processing. An external combination block was then used to combine the display stream portions generated by each of the graphics processors to form a composite display stream. Unfortunately, such prior art systems implement the display driver, which typically includes a digital to analog converter for generating an analog display signal, as a separate component or integrated circuit. This increases the cost associated with such an implementation. Another problem is the requirement for a high level of synchronization between the pixel clocks corresponding to each of the graphics processors. This additional requirement further increases costs and reduces the potential for implementing the system in a commercially viable manner.
Therefore, a need exists for a method and apparatus for graphics processing that utilizes two or more graphics processors in parallel in a manner that does not require an external display driver.